"Not great," was the phrase Richard Allan, Facebook's vice president of policy solutions, used to describe how Zuckerberg's no-show at the hearing looked when asked by a lawmaker. Allan is also a member of the parliament's upper chamber, the House of Lords.
"I think it's important we have this kind of engagement but I also have a role supporting my company as it tries to grapple with the issues that we're talking about today," he said.
Allan added: "And I understand as we're trying to work out where senior officers of the company should be that we should work this out."
The Facebook executive was faced with a grueling session of questioning from international politicians in the British parliament on Tuesday around how it handles user data and privacy.
Lawmakers from Britain, Canada, France, Belgium, Brazil, Ireland, Latvia, Argentina and Singapore questioned Facebook's policy head.
A seat was left vacant beside Allan with a card reading Zuckerberg's name, highlighting the lawmakers' visible frustration with the company for not sending its boss.
"We don't have Mr Zuckerberg here today which is incredible unfortunate, and I think speaks to a failure to account for the loss of trust certainly across the globe with respect to Facebook and Facebook's users," Nathaniel Erskine-Smith, vice chair of the standing committee on access to information, privacy and ethics in the lower house of Canada's parliament, told Allan at the hearing.
He added: "In the Canadian context, it wasn't until recently that you started to notify Canadian users that their information was shared in the Cambridge Analytica context. And that sense of corporate responsibility particularly one of the immense power and profit of Facebook has been as empty as the chair beside you."
Facebook began notifying users whether their data had been wrongly shared with Cambridge Analytica back in April.
The hearing, which was dubbed the "International Grand Committee," is part of the U.K. Digital, Culture, Media and Sport (DCMS) select committee's inquiry into disinformation and fake news.
The committee's focus has become increasingly centered on Facebook, which found itself at the heart of a scandal surrounding the way user information was improperly shared with Cambridge Analytica, the controversial political consultancy that helped President Donald Trump's campaign during the 2016 presidential election.
The social media giant was fined £500,000 by the Information Commissioner's Office, the U.K.'s data regulator, for failing to protect user data. However, Facebook has said it will appeal this fine, arguing that the ICO found no evidence that British data had been shared with Cambridge Analytica.
Last weekend, British parliament made the unusually aggressive decision to seize internal Facebook documents from U.S. businessman Ted Kramer, founder of controversial app maker Six4Three. The documents were reportedly obtained by Kramer's lawyers as a result of legal discovery ahead of a court case between Six4Three and Facebook.
Now-defunct Six4Three developed an app called Pikinis, which let people pay to find pictures of Facebook users in swimsuits. The app was shut down in 2015 after Facebook changed its policies around the sharing of user data with third-party developers. Six4Three argues that Facebook drove developers away through anti-competitive means — Facebook disputes that claim, calling it "entirely meritless."
The documents are reported to contain confidential emails related to Facebook's data and privacy controls, as well as correspondence with Zuckerberg and other senior executives at the company.
Damian Collins, chair of the DCMS select committee, has said the papers could be released; however, Facebook's Allan told the British lawmaker that, as they are under judicial consideration, they should be kept out of the public eye.
Collins has repeatedly called on Facebook's Zuckerberg to appear before the committee, only to be rejected multiple times. The highest-level Facebook executive to have appeared before the committee so far was Mark Schroepfer, the firm's chief technology officer, who in April admitted the company "did not read all of the terms and conditions" of the app responsible for improperly sharing user data with Cambridge Analytica.
Correction: This story has been updated to correct the name of Richard Allan, Facebook's vice president of public policy.